Cylindrical base, master and master manufacturing method

ABSTRACT

Provided are a cylindrical base, a master and a method for manufacturing a master enabling a uniform transfer of a fine pattern. A cylindrical base of a quartz glass having an internal strain in terms of birefringence of less than 70 nm/cm is used. A resist layer is deposited to an outer circumference surface of this cylindrical base, a latent image is formed on the resist layer, the latent image formed on the resist layer is developed and the pattern of the developed resist layer is used as a mask for etching to form a structure including concaves or convexes arranged in a plurality of rows on the outer circumference surface of the cylindrical base.

This application is a Continuation of U.S. application Ser. No.15/950,596, filed Apr. 11, 2018, which is a Divisional of U.S.application Ser. No. 15/026,509 filed Mar. 31, 2016, which is a NationalStage of International Application No. PCT/JP2014/082171 filed Dec. 4,2014, which claims the benefit of Japanese Application No. 2013-264358filed Dec. 20, 2013. The disclosures of the prior applications arehereby incorporated by reference herein in their entireties.

TECHNICAL FIELD

The present invention relates to a cylindrical base, a master and amethod for producing a master for transferring a fine pattern onto suchmaterials as light-curing resin.

BACKGROUND ART

Conventionally, a surface treatment is performed on optical elementsusing a transparent base material such as glass or plastic to reducesurface reflection of light. As such a surface treatment, a methodexists for manufacturing a fine concave/convex pattern (for example, amoth eye pattern) on an optical element surface (for example, refer toPLT 1 and 2).

In these techniques, a master having a desired pattern formed on thesurface thereof is used and transferring the pattern of the master to asheet coated with, for example, a photosensitive resin or athermosetting resin, enables inexpensive and mass production.

Furthermore, there is a method of forming a desired pattern on acylindrical shaped quartz base using mastering techniques for opticaldiscs. In this case, thermal lithography using thermal changes in aninorganic resist (for example, metal oxides made from one or moretransition metals such as tungsten and molybdenum, among others) can beused. By using thermal lithography, thermal reaction is caused in only acentral portion of the beam width which enables machining of a finepattern exceeding the resolution limit of the laser light.

However, in exposure using mastering techniques for optical discs,variances in surface properties (waviness and unevenness) and shape(roundness) lead to adverse changes in exposure beam conditions.Furthermore, in the case of using thermal lithography, interactionbetween strain in the quartz base material and heating of the inorganicresist degrades pattern precision.

PRIOR ART LITERATURE Patent Literatures

-   PLT 1: Japanese Unexamined Patent Application Publication No.    2009-199086-   PLT 2: Japanese Unexamined Patent Application Publication No.    2010-156843

SUMMARY OF INVENTION Technical Problem

In view of the foregoing, an object of the present invention is toprovide a cylindrical base, a master and a method for manufacturing amaster which enable uniform transfer of a fine pattern.

Solution to Problem

As the result of intensive studies, it has been found by the presentinventors that using a cylindrical base having a small internal strainenables transfer of a fine pattern with a high precision and accuracy.

Accordingly, a cylindrical base according to the present invention ismade of a cylindrically shaped quartz and internal strain of thecylindrical base in terms of birefringence is less than 70 nm/cm.

Additionally, a master according to the present invention includes theabove-mentioned cylindrical base and a structure having convexes orconcaves formed on the outer circumference surface of the cylindricalbase.

Additionally, a method for manufacturing a master according to thepresent invention includes a resist depositing step of depositing aresist layer onto the outer circumference surface of the cylindricalbase, an exposure step of forming a latent image on the resist layer, adeveloping step of developing the resist layer having the latent imageformed thereon, and an etching step of etching the cylindrical base byusing a pattern of the developed resist layer as a mask to form astructure having a plurality of concaves or convexes onto the outercircumference surface of the cylindrical base.

Additionally, a method for manufacturing an optical element fortransferring the structure of the above-mentioned master to alight-curing resin layer according to the present invention includessteps of bringing the light-curing resin layer tightly in contact withan outer circumference surface of the master, curing the light-curingresin and peeling off the light-curing resin.

Advantageous Effects of Invention

According to the present invention, because internal strain within thecylindrical base is small, surface fluctuations caused by heat aresmall, enabling uniform transfer of a fine pattern.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic perspective view illustrating a cylindrical base.

FIG. 2A is a perspective view illustrating one example of aconfiguration of a roll master and FIG. 2B is an enlarged plan viewillustrating a portion of a surface of the roll master illustrated inFIG. 2A.

FIG. 3 is a schematic view illustrating one example of a configurationof an exposure device for manufacturing a roll master.

FIG. 4 is a schematic view illustrating one example of a configurationof an etching device for manufacturing a roll master.

FIG. 5A is a schematic cross-sectional view illustrating a cylindricalbase, FIG. 5B is a schematic cross-sectional view illustrating acylindrical base having a resist layer deposited on an outercircumference surface thereof and FIG. 5C is a schematic cross sectionalview illustrating a cylindrical base in which the resist layer has beenexposed.

FIG. 6A is a schematic cross-sectional view illustrating a cylindricalbase having a developed resist layer and FIG. 6B is a cross-sectionalview illustrating a cylindrical base which has been etched.

FIG. 7 is a schematic view illustrating one example of a configurationfor a transfer device.

FIG. 8 is an image representing internal strain of a cylindrical base ofExample 1.

FIG. 9 is a two-dimensional image representing a reflected lightintensity distribution of a master of Example 1.

FIG. 10 is an SEM image representing a pattern arrangement of a masterof Example 1.

FIG. 11 is an image representing internal strain of a cylindrical baseof Comparative Example 1.

FIG. 12 is a two-dimensional image representing a reflected lightintensity distribution of a master of Comparative Example 1.

FIG. 13 is an SEM image representing a pattern arrangement of a masterof Comparative Example 1.

FIG. 14 is a graph representing surface waviness on a cylindrical baseof Example 2.

FIG. 15 is a two-dimensional image representing a reflected lightintensity distribution of a master of Example 2.

FIG. 16 is a graph representing surface waviness on a cylindrical baseof Comparative Example 2.

FIG. 17 is a two-dimensional image representing a reflected lightintensity distribution of a master of Comparative Example 2.

DESCRIPTION OF EMBODIMENTS

An embodiment of the present invention will now be more particularlydescribed with reference to the accompanying drawings according to thefollowing order.

1. Cylindrical Base and Master 2. Method for Manufacturing a Master 3.Method for Manufacturing an Optical Element 4. Examples 1. CylindricalBase and Master

Cylindrical Base

FIG. 1 is a schematic perspective view illustrating a cylindrical base.A cylindrical base 11 is made of a quartz glass in a cylindrical shapeand is particularly suitable for use as a hollow cylindrical roll moldhaving a fine pattern formed on the outer circumference surface thereof.As long as SiO₂ purity is high, either fused quartz glass or syntheticquartz glass may be used as the quartz glass without particularlimitation.

Furthermore, size of the cylindrical base 11, while being withoutparticular limitation, may be selected according to use and, forexample, may be a length L in the axial dimension of 100 mm or more, anouter diameter D of between 50 and 300 mm and a thickness T of between 2and 50 mm.

Internal strain in terms of birefringence in the cylindrical base 11 isless than 70 nm/cm and more preferably 20 nm/cm or less. For example, inthe case of using thermal lithography in exposing a desired pattern,smaller internal strain in the cylindrical base 11 will reduce surfacefluctuations caused by heat and will suppress disarrangement of thepattern. Furthermore, in the case of exposing a moth eye pattern as ananti-reflection pattern, for example, it is possible to achieve auniform in-plane distribution of the anti-reflection property. Moreover,generation of cloudy regions due to scattering of transmitted lightcaused by disarrangement of the pattern arrangement can be prevented.

Internal strain of this cylindrical base 11 is, for example, measuredwith a strain measuring instrument which measures birefringence causedby residual stress within a transparent body and is ordinarily expressedin terms of retardation per 1 cm of thickness (unit: nm/cm).

Waviness having a period of 10 mm or less in the circumferentialdirection on the outer circumference surface of the cylindrical base 11preferably has an amplitude of less than 100 nm and more preferably 50nm or less. In the case of using an exposure device having aconfiguration based on an optical disc recording device to draw thedesired pattern on the cylindrical base 11 on which a resist has beendeposited, because waviness on the outer circumference surface of thecylindrical base 11 in the circumferential direction having a period of10 nm or less has an amplitude of less than 100 nm, tracking is possiblewith a focus servo mechanism of the exposure device which can suppresssize fluctuations in an exposed pattern. For example, in the case ofexposing a moth eye shaped anti-reflection pattern, a uniform in-planedistribution of the anti-reflection property can be achieved.

Waviness in the circumferential direction on the outer circumferencesurface of the cylindrical base 11 can be determined by measuring thecurved surface of the cylinder to obtain coordinate data, for example,by using a stylus-type surface roughness measuring device.

Master

FIG. 2A is a perspective view illustrating one example of aconfiguration of a roll master and FIG. 28 is an enlarged plan viewillustrating a portion of the surface of the roll master illustrated inFIG. 2A. This master 10, known as a roll master, includes thecylindrical base 11 and a structure 12 comprising a plurality ofconcaves or convexes arranged on the outer circumference surface of thecylinder substrate 11.

The structure 12 has a plurality of tracks T with a pitch P which isequal to or narrower than the wavelength of light in the intendeduse-environment for the target optical element, for example,approximately the wavelength of visible light, arranged to form atwo-dimensional periodic array or, for example, arranged in concentriccircles or in a spiral on the surface of the cylindrical base 11.Furthermore, the structure 12 may be arranged in a selected regularpattern such as, for example, a tetragonal lattice or a hexagonallattice. Additionally, height of the structure 12 on the surface of thecylindrical base 11 may fluctuate regularly or irregularly.

2. Method for Manufacturing a Master

A method for manufacturing a master according to the present inventionwill now be explained. The method for manufacturing a master accordingto this embodiment includes a resist depositing step of depositing aresist layer onto the outer circumference surface of the above-describedcylindrical base, an exposure step of forming a latent image on theresist layer, a developing step of developing the resist layer havingthe latent image formed thereon, and an etching step of etching thecylindrical base by using a pattern of the developed resist layer as amask to form a structure having a plurality of concaves or convexes ontothe outer circumference of the cylindrical base.

Because the cylindrical base used in this embodiment has an internalstrain in terms of birefringence of less than 70 nm/cm, the exposurestep in which a laser light is irradiated to the resist layer to form alatent image can be advantageously used. Additionally, using, forexample, metal oxides of one or more transition metals such as tungstenand molybdenum, among others, as an inorganic resist, the exposure stepof forming a latent image by using thermal lithography which usesthermal changes in the resist layer can be advantageously used. Thus,thermal reaction is caused in only the central portion of the beam widthand a fine pattern exceeding the resolution limit of the laser light canbe machined. Furthermore, to achieve a structure having a high aspectratio, dry etching is preferably used.

Example device configurations for a usable exposure device for theexposure step and a usable etching device for the etching step are givenbelow.

Exposure Device

FIG. 3 is a schematic view illustrating one example of a configurationof an exposure device for manufacturing a roll master. This exposuredevice has a configuration based on an optical disc recording device.

A laser light source 21 is a light source for exposing the resist whichis deposited as a recording medium on the surface of the cylindricalbase 11 and emits a recording laser light 20 having, for example, awavelength λ of 266 nm. The laser light 20 emitted by the laser lightsource 21 proceeds as a collimated beam and enters an electro-opticmodulator (EOM) 22. The laser light 20 which has passed through theelectro-optic modulator 22 is reflected by a mirror 23 and guided intoan optical modulation system 25.

The mirror 23 comprises a polarizing beam splitter which reflects onepolarization component and transmits the other polarization component.The polarization component transmitted through the mirror 23 is receivedby a photo diode 24 and, on the basis of this received light signal,phase modulation controlled by the electro-optic modulator 22 isperformed on the laser light 20.

In the optical modulation system 25, the laser light 20 is collected bya condenser lens 26 into an acousto-optic modulator 27 (AOM) made fromsuch a material as a glass (SiO₂). The laser light 20, after beingintensity modulated and diverged in the acousto-optic modulator 27, iscollimated by a collimator lens 28. The laser light 20 emitted from theoptical modulation system 25 is reflected by a mirror 31 and led to amovable optical table 32 in a horizontal and parallel manner.

The movable optical table 32 includes a beam expander 33 and anobjective lens 34. The laser light 20 led to the movable optical table32 is adjusted by the beam expander 33 into a desired beam shape andthen is irradiated via the objective lens 34 to the resist layer on thecylindrical base 11. The cylindrical base 11 is positioned on aturntable 36 which is connected to a spindle motor 35. While thecylindrical base 11 is rotated, the resist layer is intermittentlyirradiated with the laser light 20 while moving the laser light 20 inthe height direction of the cylindrical base 11 to perform the exposurestep of the resist layer. For example, the latent image formed is ofapproximately elliptical shapes in which the major axes are in thecircumferential direction. Movement of the laser light 20 isaccomplished by moving the movable optical table 32 in the directionindicated by the arrow R.

The exposure device includes, for example, a control mechanism 37 forforming a latent image of a two-dimensional pattern such as a hexagonallattice or quasi-hexagonal lattice on the resist layer. The controlmechanism 37 includes a formatter 29 and a driver 30. The formatter 29includes a polarity inverter and this polarity inverter controls timingof irradiation of the laser light 20 to the resist layer. The driver 30receives an output from the polarity inverter and controls theacousto-optic modulator 27.

In this exposure device, in order to create a spatially-linkedtwo-dimensional pattern, a signal is generated once per track tosynchronize the polarization inverting formatter signal and a rotationcontroller of the recording device, and intensity modulation isperformed by the acousto-optic modulator 27. By patterning with anappropriate rotation speed at a constant angular velocity (CAV), anappropriate modulation frequency and an appropriate feed pitch, atwo-dimensional pattern such as a hexagonal lattice or a quasi-hexagonallattice can be recorded onto the resist layer.

Etching Device FIG. 4 is a schematic view illustrating one example of aconfiguration of an etching device for manufacturing a roll master. Theetching device, which is known as an RIE (Reactive ion Etching) device,as illustrated in FIG. 4, includes an etching reaction chamber 41, acylindrical electrode 42 which is a cathode and a counter electrode 43which is an anode. The cylindrical electrode 42 is located in a centralportion of the etching reaction chamber 41. The counter electrode 43 isprovided on an inner side of the etching reaction chamber 41. Thecylindrical electrode 42 is configured to enable removable attachment ofthe cylindrical base 11. For example, the cylindrical electrode 42 has acylinder surface which corresponds to or is approximately the same asthe cylinder surface of the cylindrical base 11 and, in particular, hasa slightly smaller diameter than the inner diameter of the cylindricalbase 11. The cylindrical electrode 42 is connected via a blockingcapacitor 44 to a high frequency power source (RF) 45 having, forexample, a frequency of 13.56 MHz. The counter electrode 43 is connectedto a ground.

In this etching device, when a high frequency voltage is applied betweenthe counter electrode 43 and the cylindrical electrode 42 by the highfrequency power source 45, a plasma is generated between the counterelectrode 43 and the cylindrical electrode 42. Because the counterelectrode 43 is connected to a ground, electrical potential thereof doesnot change; contrastingly, a negative electric potential occurs in thecylindrical electrode 42 because the circuit is isolated by the blockingcapacitor 44 and a voltage drop is generated. This voltage drop causesan electric field to be generated in the direction perpendicular to thecylinder surface of the cylindrical electrode 42 and plasma ions withinthe plasma perpendicularly collide with the outer circumference surfaceof the cylindrical base 11 and, thus, anisotropic etching is performed.

Steps of Method for Manufacturing a Master

Steps of a method for manufacturing a master according to thisembodiment will now be explained in order with reference to FIGS. 5 and6.

Resist Depositing Step

First, as illustrated in FIG. 5A, the previously mentioned cylindricalbase 11 is prepared. This cylindrical base 11 is, for example, made of aquartz glass. Next, as illustrated in FIG. 5B, a resist layer 13 isdeposited onto the outer circumference surface of the cylindrical base11. As the material for the resist layer, for example, either an organicresist or an inorganic resist may be used. Examples of organic resistsinclude, for example, novolac-type resists and chemically amplifiedresists. Examples of inorganic resists include, for example, metaloxides made from one or more transition metals such as tungsten andmolybdenum.

Exposure Step

Next, using the exposure device illustrated in FIG. 3, while thecylindrical base 11 is rotated, a laser light (exposure beam) 20 isirradiated to the resist layer 13. At this time, while the laser light20 is moved in the height direction (the direction parallel with thecentral axis) of the cylindrical base 11, by intermittently irradiatingthe laser light 20, the resist layer 13 is exposed across the entiresurface thereof. As illustrated in FIG. 5C, a latent image 14corresponding to the trace of the laser light 20 and having a pitchwhich is approximately the same as the wavelength of visible light isthereby formed on the entire surface of the resist layer 13. The latentimage 14, for example, comprises tracks arranged in a plurality of rowsand forms a hexagonal pattern or quasi-hexagonal pattern on the outercircumference surface of the cylindrical base 11. For example, thelatent image 14 has, for example, an elliptical shape having a majoraxis in the direction to which the tracks extend.

Developing Step

Next, a developer is applied to the resist layer 13 to develop theresist layer 13. In the case of using a positive resist to form theresist layer 13, because exposed portions exposed to the laser light 20have an increased dissolution rate in the developer in comparison tounexposed portions, as illustrated in FIG. 6A, a pattern correspondingto the latent image 14 (exposed portions) is formed in the resist layer13.

Etching Step

Next, using the pattern (resist pattern) of the resist layer 13 formedon the cylindrical base 11 as a mask, the surface of the cylindricalbase 11 is etched. As illustrated in FIG. 6B, concaves can thereby beformed which have an elliptical conic shape or an elliptical frustumshape having a major axis in the direction to which the tracks extend,thus achieving a structure 12. As the etching method, either dry etchingor wet etching may be used; however, dry etching using, for example, theetching device illustrated in FIG. 4, is preferable. By using dryetching, a glass master having a depth of three times or more of that ofthe resist layer 13 (a selection ratio of three or more) can bemanufactured and a high aspect ratio is achievable in the structure 12.

By the above, a master 10 having, for example, a hexagonal orquasi-hexagonal pattern with concaves of a depth from approximately 200nm to approximately 350 nm can be obtained.

3. Method for Manufacturing an Optical Element

In a method for manufacturing an optical element according to thisembodiment, a light-curing resin layer is brought tightly in contactwith the outer circumference surface of the master described above andthe light-curing resin layer is peeled away ater curing to transfer thestructure of the master to the light-curing resin layer.

FIG. 7 is a schematic view illustrating one example of a configurationfor a transfer device. The transfer device includes the cylindricalmaster 10, a backing supply roller 51, a take-up roller 52, guiderollers 53, 54, a nip roller 55, a peeling roller 56, an applicationdevice 57 and a light source 58.

A backing 61 in, for example, a sheet form, is wound around the backingsupply roller 51 in a roll form and the backing 61 is arranged so as toenable continuous feeding therefrom via the guide roller 53. The take-uproller 52 is arranged to enable taking up of a laminated material havinga resin layer 62 to which a concave/convex pattern has been transferredby this transfer device. The guide rollers 53, 54 are located in atransport route of this transfer device to transport the laminatedmaterial of the backing 61 and the resin layer 62. The nip roller 55 isarranged to enable nipping of the backing 61, which is fed from thebacking supply roller 51 and has a light-curing resin compositionapplied thereon, and the master 10, which is in a roller form. Themaster 10 has a transfer surface for forming the resin layer 62. Thepeeling roller 56 is arranged to enable peeling of the resin layer 62,obtained by curing the light curing resin composition, from the transfersurface of the master 10.

Materials for the backing supply roller 51, the take-up roller 52, theguide rollers 53, 54, the nip roller 55, and the peeling roller 56,while being without particular limitation, can be selected asappropriate and according to desired roller characteristics from metalssuch as stainless steel and materials such as rubber and silicone. Asthe application device 57, for example, a device such as a coater havingan application means can be used. As the coater, for example, withconsideration to the properties of the light-curing resin composition tobe applied, a coater can be selected as appropriate from such types asgravure, wire bar and die, among others.

By using such a transfer device, the structure 12 of the master 10 canbe continuously replicated to a resin sheet.

Material used in the backing 61, on the condition that it be atransparent material, is without particular limitation and, for example,a material having a transparent resin composition such as polycarbonate(PC) or polyethylene terephthalate (PET) or a glass as a primaryconstituent may be used.

The light-curing resin composition is made, for example, from materialsincluding monofunctional monomers, bifunctional monomers, polyfunctionalmonomers, and initiators, in particular, the materials listed below maybe used individually or blended in a combination of two or more.

Examples of usable monofunctional monomers include, for example,carboxylic acid (acrylic acid), hydroxy compounds (2-hydroxyethylacrylate, 2-hydroxypropyl acrylate and 4-hydroxybutyl acrylate),alkyl/alicyclic compounds (isobutyl acrylate, t-butyl acrylate, isooctylacrylate, lauryl acrylate, stearyl acrylate, isobornyl acrylate andcyclohexyl acrylate), other functional monomers (2-methoxyethylacrylate, methoxyethylene glycol acrylate, 2-ethoxyethyl acrylate,tetrahydrofurfuryl acrylate, benzyl acrylate, ethyl carbitol acrylate,phenoxyethyl acrylate, N, N-dimethylaminoethyl acrylate, N,N-dimethylaminopropyl acrylamide, N, N-dimethyl acrylamide, acryloylmorpholine. N-isopropyl acrylamide, N, N-diethyl acrylamide,N-vinylpyrrolidone, 2-(perfluorooctyl)ethyl acrylate, 3-perfluorohexyl2-hydroxypropyl acrylate, 3-perfluorooctyl-2-hydroxypropyl acrylate,2-(perfluorodecyl)ethyl acrylate and 2-(perfluoro-3-methylbutyl)ethylacrylate), 2,4,6-tribromophenyl acrylate, 2,4,6-tribromophenylmethacrylate, 2-(2,4,6-tribromophenoxy)ethyl acrylate and 2-ethylhexylacrylate, among others.

Examples of usable bifunctional monomers include, for example,tri(propylene glycol) diacrylate, trimethylolpropane diallyl ether andurethane acrylate, among others.

Examples of polyfunctional monomers include, for example,trimethylolpropane triacrylate, dipentaerythritol penta/hexa acrylateand di-trimethylolpropane tetraacrylate, among others.

Examples of usable initiators include, for example,2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxycyclohexyl phenyl ketoneand 2-hydroxy-2-methyl-1-phenylpropan-1-one, among others.

In addition, the light-curing resin composition may include, asnecessary, fillers, functional additives, solvents, inorganic materials,pigments, antistatic agents, and sensitizing dyes, among others. As afiller, for example, fine inorganic particles or fine organic particlesmay be used. Examples of fine inorganic particles include fine metaloxide particles such as those of SiO₂, TiO₂, ZrO₂, SnO₂, and Al₂O₃,among others. Examples of functional additives include, for example,leveling agents, surface conditioners, absorbents, and antifoamingagents, among others.

EXAMPLES 4. Examples

Examples of the present invention will now be described. In theseexamples, masters were manufactured using cylindrical bases havingdiffering internal strain and surface waviness and the reflected lightintensity distribution and pattern arrangement thereof were evaluated.It should be noted that the present invention is not limited by theseexamples. Cylindrical base strain measurements, cylindrical base surfacewave measurements, master reflected light intensity distributionobservations and master pattern arrangement observations were performedas the following manner.

Cylindrical Base Internal Strain Measurement

A strain measuring instrument (SVP vertical model manufactured by AGCTechno Glass Co., Ltd.) was used to measure internal strain in thecylindrical bases.

Cylindrical Base Surface Waviness Measurement A surface profiler (FormTalysurf PGI 1250A manufactured by Taylor Hobson Ltd) was used tomeasure surface waviness on the cylindrical bases.

Master Reflected Light Intensity Distribution Measurement

The masters were rotated while a measuring head having a laser (λ=650nm) and a light receiving element (photo diode, PD) was moved in theheight direction of the master to measure intensity of reflected laserlight; the measurements were logged and mapped to create atwo-dimensional image of reflected light intensity distribution of themasters.

Master Pattern Arrangement Observation

A scanning electron microscope (SEM) was used to observe mastersurfaces.

Example 1

A cylindrical base made of a quartz glass was prepared in which aninternal strain was less than 20 nm/cm and waviness on the outercircumference surface thereof having a period of 10 mm or less had anamplitude of 100 nm or less. FIG. 8 is an image representing internalstrain of the cylindrical base of Example 1. A color image correspondingto the amount of birefringence caused by internal residual stress wasobtained with the strain measuring instrument and indicated an internalstrain of less than 20 nm/cm.

A resist layer made from a metal oxide of tungsten was deposited on theouter surface of this cylindrical base. Subsequently, using an exposuredevice, a latent image of a quasi-hexagonal pattern was patterned ontothe resist by using thermal lithography using a laser light. Next, theresist layer on the cylinder base was developed and exposed portions ofthe resist were dissolved. A resist master was thereby obtained in whichthe resist layer was open in a quasi-hexagonal pattern. Next, using theetching device, the resist master was etched by RIE to form concavesextending in the direction perpendicular to the surface of the glassroll. Finally, ashing was performed to completely remove the resistpattern. Thus, the target glass roll master (the master) was obtained.

FIGS. 9 and 10 are, respectively, a two-dimensional image representingreflected light intensity distribution of the master of Example 1 and anSEM image of a pattern arrangement of the master of Example 1. Asillustrated in FIG. 9, the master of Example 1 had a uniform reflectedlight intensity distribution and, as illustrated in FIG. 10,disarrangement of the pattern did not occur.

Comparative Example 1

A cylindrical base made of a quartz glass was prepared which included astripe-shaped region having an internal strain of approximately 70 nm/cmand in which waviness on the outer circumference surface thereof havinga period of 10 mm or less had an amplitude of 100 nm or less. FIG. 11 isan image representing internal strain of the cylindrical base ofComparative Example 1. A color image corresponding to the amount ofbirefringence caused by internal residual stress was obtained with thestrain measuring instrument which indicated a region having an internalstrain of approximately 70 nm/cm. Using this cylindrical base, a glassroll master (master) was manufactured in the same manner as in Example1.

FIGS. 12 and 13 are, respectively, a two-dimensional image representingreflected light intensity distribution of the master of ComparativeExample 1 and an SEM image of a pattern arrangement of the master ofComparative Example 1. As illustrated in FIG. 12, the master ofComparative Example 1 had a stripe-shaped reflected light intensitydistribution. Additionally, clouded regions were observed uponinspecting transparency. Furthermore, as illustrated in FIG. 13,disarrangement of the pattern occurred in stripe-shaped regions.

Example 2

A cylindrical base made of a quartz. glass was prepared in which aninternal strain was less than 20 nm/cm and waviness on the outercircumference surface thereof having a period of 10 mm or less had anamplitude of approximately 50 nm. FIG. 14 is a graph representingsurface waviness on the cylindrical base of Example 2. Waviness on theouter circumference surface in the circumferential direction in Example2 had a small amplitude of approximately 50 nm. Using this cylindricalbase, a glass roll master (master) was manufactured in the same manneras in Example 1.

FIG. 15 is a two-dimensional image representing reflected lightintensity distribution of the master of Example 2. As illustrated inFIG. 15, the master of Example 2 had a uniform distribution of reflectedlight intensity.

Comparative Example 2

A cylindrical base made of a quartz glass was prepared in which aninternal strain was less than 20 nm/cm and waviness on the outercircumference surface thereof having a period of 10 mm or less and anamplitude of approximately 100 nm. FIG. 16 is a graph representingsurface waviness on the cylindrical base of Comparative Example 2.Waviness on the outer circumference surface in the circumferentialdirection in Comparative Example 2 had a pitch of 5 mm and an amplitudeof approximately 100 nm. Using this cylindrical base, a glass rollmaster (master) was manufactured in the same manner as in Example 1.

FIG. 17 is a two-dimensional image representing reflected lightintensity distribution of the master of Comparative Example 2. Asillustrated in FIG. 17, a characteristic striped pattern occurred alongwaviness in the reflected light intensity distribution of the master ofComparative Example 2.

Evaluation Results

As seen in Comparative Example 1, using thermal lithography methodsusing thermal changes in the resist material, when exposing the desiredpattern, in the case of internal strain in the cylindrical base being 70nm/cm or more, the surface of the quartz fluctuates during exposurethereby causing disarrangement of the exposed pattern; thus, astripe-shaped distribution of reflected light intensity was generated.In addition, clouded regions caused by scattering of transmitted lightdue to pattern disarrangement were observed when inspectingtransparency.

Contrastingly, as seen in Example 1, in the case of internal strain inthe cylindrical base being less than 70 nm/cm, disarrangement of theexposed pattern was suppressed, a uniform in-plane distribution ofreflected light intensity was achieved and clouded regions caused byrefracted light did not occur.

Moreover, as seen in Comparative Example 2, in the case of waviness onthe outer circumference surface of the cylindrical base in thecircumferential direction with a period of 10 mm or less having anamplitude of 100 nm or more, when drawing a desired pattern, trackingwith the focus servo mechanism is not possible which caused fluctuationsin the size of the exposed pattern which generated a characteristicstriped pattern along waviness in the reflected light intensitydistribution.

Contrastingly, as seen in Example 2, in the case of waviness on theouter circumference surface of the cylindrical base in thecircumferential direction with a period of 10 mm or less having anamplitude of less than 100 nm, it was possible to control fluctuationsin the size of the exposed pattern and achieve a uniform reflected lightintensity distribution.

REFERENCE SIGNS LIST

-   -   10 master, 11 cylindrical base, 12 structure, 13 resist layer,        14 latent image, 20 laser light, 21 laser light source, 22        electro-optic modulator, 23 mirror, 24 photo diode, optical        modulation system, 26 condenser lens, 27 acousto-optic        modulator, 28 collimator lens, 29 formatter, 30 driver, 31        mirror, 32 movable optical table, 33 beam expander, 34 objective        lens, 35 spindle motor, 36 turntable, 37 control mechanism, 41        etching reaction chamber, 42 cylindrical electrode, 43 counter        electrode, 44 blocking capacitor, 45 high frequency power        source, 51 backing supply roller, 52 take-up roller, 53, 54        guide roller, 55 nip roller, 56 peeling roller, 57 application        device, 58 light source, 61 backing, 62 resin layer

1. A cylindrical base comprising a quartz glass in a cylindrical shape,wherein the cylindrical base has an internal strain in terms ofbirefringence of less than 70 nm/cm, waviness on an externalcircumference surface thereof having a period of 10 mm or less in thecircumferential direction has an amplitude of 100 nm or less, an outerdiameter of between 50 and 300 mm and a thickness of between 2 and 50mm.
 2. The cylindrical base according to claim 1, wherein the internalstrain in terms of birefringence is less than 20 nm/cm.
 3. Thecylindrical base according to claim 2, wherein waviness on an externalcircumference surface thereof having a period of 10 mm or less in thecircumferential direction has an amplitude of 50 nm or less.
 4. Thecylindrical base according to claim 1, wherein waviness on an externalcircumference surface thereof having a period of 10 mm or less in thecircumferential direction has an amplitude of 50 nm or less.
 5. Thecylindrical base according to claim 1, wherein the cylindrical base isused for thermal lithography in exposing a desired pattern.
 6. A mastercomprising: the cylindrical base according to claim; and a structurehaving a plurality of concaves or convexes arranged on an outercircumference surface of the cylindrical base.
 7. The master accordingto claim 6, wherein the structure has a plurality of tracks with a pitchthat is equal to or narrower than a wavelength of light.